21165681277751 has 2 divisors, whose sum is σ = 21165681277752. Its totient is φ = 21165681277750.

The previous prime is 21165681277739. The next prime is 21165681277753. The reversal of 21165681277751 is 15777218656112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21165681277751 - 2⁴² = 16767634766647 is a prime.

Together with 21165681277753, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21165681277753) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10582840638875 + 10582840638876.

It is an arithmetic number, because the mean of its divisors is an integer number (10582840638876).

Almost surely, 2^{21165681277751} is an apocalyptic number.

21165681277751 is a deficient number, since it is larger than the sum of its proper divisors (1).

21165681277751 is an equidigital number, since it uses as much as digits as its factorization.

21165681277751 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9878400, while the sum is 59.

The spelling of 21165681277751 in words is "twenty-one trillion, one hundred sixty-five billion, six hundred eighty-one million, two hundred seventy-seven thousand, seven hundred fifty-one".